The invention relates to fluid valve arrangements.
Fluid valves find many industrial uses, for example moving large machinery of one kind or another, raising and lowering loads, etc. A poppet valve may be employed, for example, to control the advance or retraction of a press. Spool valves, for example, may provide for advance and retraction of such apparatus as the table of a grinder or of a press element. In these various cases there may be a way of controlling the valve outlet flow, but often the control is not readily available to the operator at his station, remote from the machine.
One of the problems associated with fluid valving is that the loads should be moved at a desirable speed, but not so rapidly as to create undesirable impacts or collisions, or the like. If the load is moved too slowly, the work is delayed; if moved too rapidly the work is endangered. To control the movement of the load at the desired pace, the flow of the working fluid through the valve must be controlled to the desired flow, neither too rapidly, nor too slowly.
Among U.S. Pat. Nos. which deal with control of loads by fluid valving are: 3,191,626 to K. W. H. Leibfritz June 29, 1965 for Valve; 3,310,068 to J. R. McGuire et al., Mar. 21, 1967 for Flow Regulator Valves and Hydraulic System; 3,565,115 to Robin K. Beckett et al, Feb. 23, 1971, for Spool Valve; 4,046,165 to Robert C. Rose Sept. 6, 1977, for Valve-Positioning Apparatus; and 4,087,967 to Knapp May 9, 1978, for Sleeve Spool Valve.